boards: shields: Add support for Mikroe BLE TINY Click shield

Add support for the Mikroe BLE TINY Click shield that contains the
Renesas DA14531 Bluetooth LE Module.

Signed-off-by: Ian Morris <ian.d.morris@outlook.com>

boards/shields/mikroe_ble_tiny_click/Kconfig.defconfig

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+# Copyright (c) 2024 Ian Morris
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_BT_HCI=y
+CONFIG_BT_HCI_ACL_FLOW_CONTROL=n
+CONFIG_BT_CTLR=n

boards/shields/mikroe_ble_tiny_click/Kconfig.shield

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+# Copyright (c) 2024 Ian Morris
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_MIKROE_BLE_TINY_CLICK
+	def_bool $(shields_list_contains,mikroe_ble_tiny_click)

boards/shields/mikroe_ble_tiny_click/doc/index.rst

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+.. _mikroe_ble_tiny_click_shield:
+
+MikroElektronika BLE TINY Click
+###############################
+
+Overview
+********
+
+The MikroElektronika BLE TINY Click carries the Renesas `DA14531MOD`_ Bluetooth
+LE module in a `mikroBUS`_ |trade| form factor.
+
+.. figure:: ble-tiny-click.webp
+   :align: center
+   :alt: MikroElektronika BLE TINY Click
+
+   MikroElektronika BLE TINY Click (Credit: MikroElektronika)
+
+Requirements
+************
+
+This shield can only be used with a board that provides a mikroBUS |trade|
+socket and defines the ``mikrobus_serial`` node label (see :ref:`shields`
+for more details).
+
+.. note::
+
+   The reset input on the DA14531 Module is active high and is connected to
+   the RST pin on the mikroBUS socket. On many host boards this RST pin is
+   connected to a system reset signal that is active low. This results in the
+   host system unintentionally holding the DA14531 Module in reset. This issue
+   can be overcome by removing resistor R3 on the BLE TINY Click board, see
+   the `BLE TINY Click Schematic`_ for further details.
+
+The DA14531 Module contained on the shield must be programmed with a binary
+file that supports the HCI interface over UART, without hardware flow control
+as these signals are not supported on the Click footprint.
+
+The `Renesas SmartBond Flash Programmer`_ tool can be used to download a
+suitable binary and then program it into the DA14531 via the SWD header
+present on the Click board. Once the tool has been installed, open it and
+press the "Search Online" button. The required binary file can be selected
+for download as follows:
+
+.. figure:: da14531-hci-binary.webp
+   :align: center
+   :alt: DA14531 HCI Binary File Selection
+
+   Selecting the DA14531 HCI Binary File for Download
+
+Press the "Program" button to program the binary file into the DA14531 Module.
+
+For more information about interfacing to the DA14531 and the BLE TINY Click,
+see the following documentation:
+
+- `DA14531MOD Datasheet`_
+- `BLE TINY Click`_
+
+Programming
+***********
+
+Set ``--shield mikroe_ble_tiny_click`` when you invoke ``west build``. For
+example:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/bluetooth/beacon
+   :board: ek-ra8m1
+   :shield: mikroe_ble_tiny_click
+   :goals: build
+
+References
+**********
+
+.. target-notes::
+
+.. _DA14531MOD:
+   https://www.renesas.com/us/en/products/wireless-connectivity/bluetooth-low-energy/da14531mod-smartbond-tiny-bluetooth-low-energy-module
+
+.. _mikroBUS:
+   https://www.mikroe.com/mikrobus
+
+.. _DA14531MOD Datasheet:
+   https://www.renesas.com/us/en/document/dst/da14531-module-datasheet?r=1601921
+
+.. _BLE TINY Click:
+   https://www.mikroe.com/ble-tiny-click
+
+.. _BLE TINY Click Schematic:
+   https://download.mikroe.com/documents/add-on-boards/click/ble_tiny_click/BLE_TINY_click_v102_Schematic.pdf
+
+.. _Renesas SmartBond Flash Programmer:
+   https://www.renesas.com/us/en/software-tool/smartbond-flash-programmer

boards/shields/mikroe_ble_tiny_click/mikroe_ble_tiny_click.overlay

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+/*
+ * Copyright (c) 2024 Ian Morris
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	chosen {
+		zephyr,bt-hci = &bt_hci_uart;
+	};
+};
+
+&mikrobus_serial {
+	status = "okay";
+
+	bt_hci_uart: bt_hci_uart {
+		compatible = "zephyr,bt-hci-uart";
+	};
+};